The eligibility may differ from university to university. But in general :

1. The student should have passed the qualifying exam i.e., (10+2) with 50% marks or above.
2. The candidate should have studied Science stream with physics , chemistry , Biology along with English in 10+2 exams. The student have to pass all the subjects individually.
3. Colleges usually take 'Entrance Test'. Although there can be exceptions.

I hope my answer helps you. Wish You all the very best for your future endeavors!